May Ends Warmest Spring in Oklahoma History

May Ends Warmest Spring in Oklahoma History

Fri. June 1, 2012

A pleasantly cool final day and scattered heavy rains during the month’s final week were too little and too late, and May entered the record books as one of the warmest and driest in state history. According to data from the Oklahoma Mesonet, the statewide average temperature finished at 72.2 degrees, 4.3 degrees above normal. That ranks May as the fifth warmest on record. Statewide average records date back to 1895. That heat, combined with the state’s warmest March and tenth warmest April, propelled the spring season to the warmest on record at 65.1 degrees, 6 degrees above normal. The climatological spring runs from March through May for record purposes. The previous record mark for spring was 62.9 degrees from 2006. The January-May statewide average of 56.3 degrees also tops the record books at 5.2 degrees above normal.

The recent warmth is a continuation of what the state has experienced since early 2010. Of the last 26 months, starting with April 2010, 21 have been warmer than normal. Three of the last 11 months (July and August, 2011, and March 2012) and two out of the last four seasons (summer 2011 and spring 2012) eclipsed their respective all-time heat records as well. June 2011 barely missed that month’s top mark, settling for the rank of second warmest. Oklahoma’s July and summer statewide average temperatures in 2011 were record marks for the United States as well. There were blasts of wintry revenge during that period, of course. Oklahoma saw its all-time lowest minimum temperature and 24-hour snowfall records fall in February 2011. Just prior to the string of warm months, the winter of 2009-10 finished as the eighth coldest – and one of the snowiest – on record at more than 4 degrees below normal.

Scattered heavy rainfall at the end of the month helped May to avoid becoming the driest on record and finished with the rank of fourth driest. The statewide average precipitation total was 1.8 inches, 3.4 inches below normal. Rainfall totals from the Mesonet ranged from around 6 inches in Grady County to a dusty 0.01 inches from both Arnett and Slapout. Much of the northern third of the state had trouble keeping the rain gauge wet and recorded less than an inch for the month. Drought relief that began last fall faded in the dry, hot weather of April and May for some areas. The latest U.S. Drought Monitor report, released on May 31, finds moderate drought creeping back into eastern Oklahoma from Arkansas. A broader area of “abnormally dry” conditions, a drought pre-cursor, covered much of eastern and southern Oklahoma. The Panhandle and southwestern Oklahoma continue with drought conditions labeled from “moderate” to “extreme.”

Despite the violent weather during its last week, May was actually one of the quietest on record for tornadoes. Preliminary numbers from the National Weather Service (NWS) estimate May’s total at three. While that number could still rise, it would not be by much. May 2010 had a record-tying 90 tornadoes and May 2011 had 46. The preliminary total for the year currently stands at 51. The average tornado count for May is 22 and the annual average is 55. Accurate tornado statistics date back to 1950.

The latest outlooks from the NWS’ Climate Prediction Center for both June and the summer months of June through August continue to indicate increased chances for above normal temperatures in Oklahoma and much of the southern United States. There are no clear signals for the state on what to expect for precipitation, however. Past that period, there are suggestions that an El Niño event could develop in the fall. That phenomenon, characterized by warmer than normal waters in the equatorial pacific, can bring cooler and wetter weather during winter to the southern tier of the United States, including Oklahoma. The last two winters have seen La Niña events enhance Oklahoma’s chances for warmer and drier weather.